# 导入整个模块
# import math
#
# if __name__ == '__main__':
#     num = math.sqrt(9)
#     print(num)

# 导入时添加别名
# import math as sx
#
# if __name__ == '__main__':
#     num = sx.sqrt(9)
#     print(num)

# 只导入某个模块中的某一个函数
# from math import sqrt
#
# if __name__ == '__main__':
#     num = sqrt(9)
#     print(num)

# 只导入某个模块中某一个函数时添加别名
# from math import sqrt as kf
#
# if __name__ == '__main__':
#     num = kf(9)
#     print(num)
